First dive at 40 meters - Newbies recreational

[Blackcrusader]

Yes, with an octopus. I thought that everyone had those nowadays.
I have made myself a very simple excel spreadsheet computing breathing minutes and depths relative to the SAC. With 75 bars and a SAC at 30, you have 6 minutes at 40 m. With a SAC at 50, almost 2 and half minutes but you don’t stay at 40.

You do not plan to stay at 40m but what happens if you have a really strong down current and you are struggling to ascend? Dive plans can be changed from other things we are not aware of at the time.

I was diving at the same dive site as the 45m dive on another and we got into a down current. One of the divers just started descending so I signaled to the DM I would go get her while he managed the other divers. The lass descending was calm as ever but she didn't realize she was going deeper as she didn't check her depth or air. She was just looking at the scenery enjoying herself. I got to her and had her follow me away from the wall into open ocean at that 45 degree angle finning to get away from the down current. I added air to my BCD and controlled the ascent for both of is and we ended up around 50m away from the wall to get away from the down current. I think we got to 38m depth but did not exceed NDL and she was confused at first she wanted to go straight up against the current and here I am pointing in a direction away from the wall. It's a small island so you can't really get lost just go around in circles but divers new to the site do not really understand that. A really strong current could take you away from the island though.

At the end of the dive she thanked me and we discussed what happened. She learned from that dive that you can get away from a current but don't try to fight it as you would just use a lot of air going nowhere. It was not a really strong current so we were lucky in that. It came all of a sudden.

 

[Dody]

You do not plan to stay at 40m but what happens if you have a really strong down current and you are struggling to ascend? Dive plans can be changed from other things we are not aware of at the time.

OOA at 40 m plus down current, this is Murphy’s law. If both buddies have OOA and down current, it is a message that someone up there wants to meet early . But I get the point.

 

[Blackcrusader]

OOA at 40 m plus down current, this is Murphy’s law. If both buddies have OOA and down current, it is a message that someone up there wants to meet early . But I get the point.

I did not mean OOA but you can have a leak or free flow. Leaks and free flows are not OOA. If both people are OOA at 40m well that's not fun. If I was at 40m in OOA situation say which may be due to say equipment failure there is a way in an extreme emergency to get to the surface alone if your dive buddy was not there to assist but I do not want to discuss that in this thread. Being self reliant and cheating death in extreme circumstances is why some people live. Like cutting off your arm when a large boulder crushes you on a walk and pins you to a wall and to survive you need to get help. To get help you need to cut your arm off as that chap in the USA did.

Aron Ralston - Wikipedia

 

[Dody]

I did not mean OOA but you can have a leak or free flow. Leaks and free flows are not OOA. If both people are OOA at 40m well that's not fun. If I was at 40m in OOA situation say which may be due to say equipment failure there is a way in an extreme emergency to get to the surface alone if your dive buddy was not there to assist but I do not want to discuss that in this thread. Being self reliant and cheating death in extreme circumstances is why some people live. Like cutting off your arm when a large boulder crushes you on a walk and pins you to a wall and to survive you need to get help. To get help you need to cut your arm off as that chap in the USA did.

Aron Ralston - Wikipedia

Can you please create a thread or send direct info about how to deal with OOA alone at 40 m? Knowledge does not kill. I do not plan to dive solo ever but it might be useful someday

 

[David Novo]

In a cave yes. But i dive mostly quarrys, where i can ascent any time. I just need enough air to bring me and my gf back to the surface. So at 120 we start to ascent and usually go back during the ascent.

But you are right, this might confuse other readers..

In a cave, you use thirds or even 1/6.
The example I gave is for when is desirable but not mandatory to return to the starting point.

 

[David Novo]

Can you please create a thread or send direct info about how to deal with OOA alone at 40 m? Knowledge does not kill. I do not plan to dive solo ever but it might be useful someday

 

[Raphus]

Can you please create a thread or send direct info about how to deal with OOA alone at 40 m? Knowledge does not kill. I do not plan to dive solo ever but it might be useful someday

Having redundancy..
In rec diving this is often your buddys tank.
Doubles or stage tanks would be a better choice.

Others then that.. Ascent and pray..
People did it from 40m.. But most probably wont.

 

[Dody]

Having redundancy..
In rec diving this is often your buddys tank.
Doubles or stage tanks would be a better choice.

Others then that.. Ascent and pray..
People did it from 40m.. But most probably wont.

Aluminium pony 40?

 

[Raphus]

Aluminium pony 40?

Hmm. That depends on the depth.
If i would dive regularly to 40m, i would take doubles.

But al40 is used aswell. Never used it myself, so i cant say a lot about it.

 

[Edward3c]

Good one. I did not think about a free flow. Would such a problem arise, I think that the best solution would be buddy breathing and ascending to 5 meters for the tank at the safety stop or worse (straight to the surface). With 150 bars for two, a controlled ascent could be possible, right?

Congratulations, your starting to understand what I meant by an incident at the worst point in the dive. I’ve known yoke O-rings to blow when tank pressure dropped to 160 or even 100bar during a dive. On another occasion a cylinder hadn’t been opened fully and when the pressure dropped to 150bar the reg stopped delivering air on demand. Yes these are exceptional events, but they happen. If you or your wife were unlucky enough to have one, and you haven’t got a contingency plan ...
As to the BB, I understood what you meant, but my advice would be to go direct to the surface where there is unlimited air. Following the stress of a shared ascent from depth messing about with a suspected tank isn’t practical.